The present invention relates to a developing unit for a facsimile transceiver, printer or similar electrophotographic image forming apparatus and, more particularly, to a toner cartridge for use with such an apparatus for supplying a toner, or developer, to the developing unit.
Generally, a dry process type image forming apparatus using a toner as a developer, e.g., an electrophotographic copier has a developing unit which is supplied with a fresh toner as needed. A predominant type of system for supplying a toner to the developing unit uses a toner bottle which is filled with a toner and directly supplies it to a toner hopper included in the developing unit. This type of system, however, causes the toner to be scattered around inside the copier and thereby often disturbs the expected operations of the copier.
A toner cartridge elaborated to eliminate the above problem is disclosed in Japanese Patent Laid-Open Publication No. 93471/1984, for example. The toner cartridge taught in this Laid-Open Publication is made up of a casing having an opening, and a lid mounted on the casing to close the opening. The lid is movable along the opening of the casing to cover and uncover it. A seal is folded into two and adhered at one half thereof to the edges of the opening of the casing. A thumb piece is provided on the surface of the other half of the folded seal. The end of the other half of the seal is affixed to the outermost end of the lid. Since the lid conceals the seal, the seal is protected from damage in the event when the cartridge is transported or otherwise handled. when the lid to which the other half of the seal is affixed as mentioned above is pulled out along the opening of the casing, the seal is entirely removed from the casing to uncover the opening. The cartridge with such a configuration can be replaced with another without the toner thereof being scattered around. In addition, the operator can remove the seal from the casing by simply pulling the thumb piece which appears as the lid is moved. This insures easy and sure supply of a fresh toner.
The prior art toner cartridge stated above is successful in freeing the seal from damage in the event of transport and in preventing the toner from being scattered around in the event of toner supply. However, the drawback with such a toner cartridge is that when the lid is moved in such a manner as to remove the seal after cartridge has been emptied, the seal having already been removed from the casing hangs down from the toner cartridge and contacts an agitator. On the other hand, assume that an arrangement is made such that the used toner is collected in a toner cartridge which has supplied a fresh toner thereof and is, therefore, empty. Then, should the lid of the cartridge filled with the use or collected toner be moved, the used toner would drop from the cartridge to contaminate the interior of the apparatus. Moreover, should the dropped used toner be mixed with the fresh toner supplied from the cartridge, it would contaminate the background or a reproduction.